1. Technical Field
The present invention generally relates to personal computer (PC) riser card architectures. More particularly, the invention relates to a riser having the ability to automatically select between a first multi-codec configuration and a second multi-codec configuration based on a codec support capability of a controller located on a motherboard.
2. Discussion
As the demand for a feature-rich computing environment continues to grow, various devices and systems have evolved to provide enhanced communication and greater mobility. For example, personal digital assistants (PDAs), wireless phones and personal computers (PCs) have all attempted to enhance communication and network functionality in some form or fashion. Indeed, the typical PC includes numerous communication subsystems in order to serve the audio, modem, and local area networking (LAN) needs of the consumer.
The conventional audio, modem or LAN application requires a coder-decoder (codec) to convert analog signals into a digital form for transmission to processing components within the PC. The codec also converts the digital signals back into an analog signal for replay over an analog channel such as a telephone line, speaker connection or networking connection. A codec controller serves as an interface between the processing components of the PC and the codec in order to implement the various features of the particular application.
It is important to note that, as the demand for applications increases so does the number of codecs communicating with the codec controller. For example, three 2-channel codecs are required in order to support six channels of “Surround Sound” audio. By integrating the codec controller and various codecs into the motherboard, less space (i.e., real estate) is available for other components. Furthermore, such an approach works against the current trend to reduced costs at all levels of the PC platform. It has additionally been determined that such an approach has the potential for increased noise, which in turn degrades the performance of each system and makes certification with authorities such as the FCC more difficult.
Thus, while earlier PCs traditionally integrated many of the above communication subsystems into the motherboard, cost, space and certification concerns dictate an alternative solution. One such solution involves the segregation of certain communication subsystems and features through the use of risers (or riser cards). A riser typically includes a printed wiring board (PWB) that is coupled through a connector (or slot) to the motherboard in a perpendicular arrangement in order to physically separate noise-sensitive systems (such as codecs) from the noisy environment of the motherboard. The riser therefore has a riser codec architecture that communicates with the codec controller resident on the motherboard. It is important to note that earlier implementations involved placing a primary codec on the motherboard and designing the riser codec architecture to incorporate a single riser codec. Thus, the codec controller could support up to two codecs when the communications riser was installed and up to one codec when the riser was not installed (unless the second codec was integrated into the motherboard). The details of such an approach can be found in Communication and Networking Riser Specification, Revision 1.1 by Intel Corporation, Oct. 18, 2000.
As the aforementioned demand for features continues to grow, however, it has been determined that it is desirable to provide multiple codecs on the communications riser. Thus, by designing the codec architecture to include two codecs instead of one, the codec controller can be configured to support up to three codecs. It should be noted, however, that systems with codec controllers having the capability to support a maximum of two codecs still exist. Thus, there is a need for a communications riser having two codecs to be able to configure itself based on the codec support capability of the codec controller resident on the motherboard. Such an ability to be backward (and forward) compatible would significantly enhance the marketability of the communications riser and would ultimately reduce design and manufacturing costs.